How nature cools the earth again.

CO2 levels

﻿During the depth of an ice age CO2 levels would be down to 180 ppm and at the peak of a warm period CO2 would rise to 300 ppm ﻿.

How marine life removes CO2

CO2 moves easily between water and the atmosphere. Just as bubbles of CO2 can be put in your beer and you can see it leave as the beer warms so it is with the atmosphere and the sea. CO2 enters the sea through surface absorption and also in great quantities by the thermohaline circulation.This CO2 in the oceans is consumed by Phytoplankton and with the action of photosynthesis the plankton use the carbon element to make their calcium carbonate structure and release oxygen into the atmosphere for us to breath. This happens in vast quantities.The Phytoplankton is eaten by the larger Zooplankton , which in turn are eaten by larger fish and eventually the carcases sink to the ocean floor and bury the carbon for ever.In this way CO2 is removed from the atmosphere and locked up.

A similar process on land

Plants absorb CO2 from the atmosphere and through the action of photosynthesis CO2 is used to make the carbon for the plants structure and oxygen is released into the atmosphere. When the tree dies the carbon enters the soil and is locked up.This is a very simplistic version of the process.

As the CO2 is removed from the atmosphere the temperature starts to fall. More ice is formed at the Poles to reflect the Suns heat from the surface and the whole cooling process is set in motion,In previous events, ice would spread down Europe, Asia and Canada and life would move closer to the Equator.